Light-emitting device, production method therefor, and display containing the same

ABSTRACT

The present invention provides a light-emitting device which includes, in the order mentioned, a light-emitting layer containing a light-emitting portion, an intermediate layer, and a fine concavo-convex pattern, wherein the intermediate layer is disposed over a second surface of the light-emitting layer which surface is opposite to a first surface of the light-emitting layer, wherein the fine concavo-convex pattern has a cross-sectional shape which has portions projected and recessed with respect to the light-emitting layer, and reflects light emitted from the light-emitting layer, and wherein at least part of the intermediate layer has a refractive index of 0.9n to 1.1n, where n denotes a refractive index of the light-emitting portion with respect to light which has a main light-emitting wavelength.

TECHNICAL FIELD

The present invention relates to a light-emitting device, a productionmethod therefore and a display containing the light-emitting device,more specifically, to light-emitting devices such as an organicelectroluminescence device (organic EL device), an inorganicelectroluminescence device (inorganic EL device) and a light emittingdiode (LED), a production method therefore, and a display containing thelight-emitting device.

BACKGROUND ART

For example, in an organic EL device 105 as shown in FIG. 3, lightbeams, which have been emitted from an EL light-emitting layer 102 laidon a reflective layer 101, are reflected on the interface between the ELlight-emitting layer 102 and a seal layer 103 or between the seal layer103 and the outside 104, leading to decrease in light-extractionefficiency.

Here, regarding the reflectivity of light on the interface at whichrefraction of the light occurs, when the interface is flat, thereflectivity depends on the incident angle of the light and thedifference in refractive index between media which share the interface.For example, when the difference in refractive index therebetween islarge, the reflectivity on the interface becomes high. Also, when lighttravels from the medium having a high refractive index to that having alow refractive index at an incident angle larger than the criticalangle, 100% of the light is reflected.

Critical angle θ_(c) is the minimum incident angle of light at which thelight is totally reflected when it travels from a substance having ahigh refractive index to that having a low refractive index, andexpressed by the equation: θ_(c)=arcsin(n₂/n₁), where n₁ denotes arefractive index of a substance through which light travels; n₂ denotesa refractive index of a substance light enters; and n₂<n₁.

FIG. 4 is an explanatory view used for describing the above phenomenon.In this figure, reference numerals 111 and 112 respectively denote afirst layer having a refractive index n₁ and a second layer having arefractive index n₂. Here, when light travels at an incident angle ofcritical angle θ_(c) with respect to a normal line (standard line) tothe interface 110 between the first and second layers, the light istotally reflected on the interface 110 and thus, cannot be extractedfrom the second layer 112. In addition, light traveling at an incidentangle of θ_(x) greater than critical angle θ_(c) with respect to thestandard line is also totally reflected on the interface 110 and thus,cannot be extracted from the second layer 112.

Meanwhile, light traveling at an incident angle of θ_(y) smaller thancritical angle θ_(c) with respect to the standard line transmits theinterface 110 to be emitted from the second layer 112 to the first layer111.

Light-emitting devices in which light is totally reflected when beingemitted from a high-refractive-index medium to a low-refractive-indexmedium pose a problem in that the light-extraction efficiency is low.

In view of this, there have been proposed light-emitting devices havingvarious structures, with which the light-extraction efficiency isattempted to be improved.

One proposed light-emitting device is an organic electroluminescencedevice including an anode, a cathode, one or more organic layerscontaining a light-emitting layer disposed between the electrodes and adiffracting grating or a zone plate, wherein the diffracting grating orthe zone plate is disposed in position for preventing total reflectionon the interface in the device (see Patent Literature 1).

Nevertheless, in the light-emitting device disclosed in PatentLiterature 1, light emitted passes through low-refractive-index layersto reach the diffracting grating or zone plate and thus, limitation isimposed on prevention of total reflection.

Also, another proposed light-emitting device contains a concavo-convexpatterned scattering layer at a back surface opposite to alight-emitting surface, wherein the scattering layer reflects/scatterslight emitted through an intermediate layer from a light-emitting layertoward the light-emitting surface for light extraction (see Non-PatentLiteratures 1 and 2).

One conventionally known light-emitting device, as shown in FIG. 5,includes a light-emitting layer 202 containing a light-emitting portion204; an intermediate layer 205; and a fine concavo-convex pattern 206 inthis order, wherein the intermediate layer and the fine concavo-convexpattern are laid over a second surface 203B of the light-emitting layer202 which surface is opposite to a first surface 203A thereof.

However, such conventional light-emitting device has a light-emittinglayer and an intermediate layer which are different in refractive index(for example, the refractive index n of the light-emitting layer: 1.8,and the refractive index n of the intermediate layer: 1.5) and thus,poses a problem in that the light-extraction efficiency from thelight-emitting layer 202 is low due to total reflection.

Specifically, light beam 210 a which is emitted from the light-emittingportion 204 to the second surface 203B of the light-emitting layer 202and whose incident angle is θ_(x) greater than critical angle θ_(c) istotally reflected on the second surface 203, and cannot be extractedfrom the light-emitting portion 204.

Also, light beam 210 b which is totally reflected on the interfacebetween the light-emitting portion 204 and a seal layer 207 toward thesecond surface 203B and whose incident angle is θ_(x) greater thancritical angle θ_(c) is totally reflected on the second surface 203B,and cannot be extracted from the light-emitting portion 204.

Furthermore, light beam 210 c which is totally reflected on the firstsurface 203A of the light-emitting layer 202 toward the second surface203B and whose incident angle is θ_(x) greater than critical angle θ_(c)is totally reflected on the second surface 203B, and cannot be extractedfrom the light-emitting portion 204.

In view of the above, demand has arisen for a light-emitting devicewhich is improved in light-extraction efficiency.

CITATION LIST Patent Literature

-   PTL 1: Japanese Patent No. 2991183

Non Patent Literature

-   NPL 1: Norihiko Kamiura, four others “Studies on OLED Light    Extraction Enhancement” edited by THE INSTITUTE OF ELECTRONICS,    INFORMATION AND COMMUNICATION ENGINEERS, TECHNICAL REPORT OF IEICE,    EID2007-102, OME2007-84 (2008-03), pp. 1 to 4-   NPL 2: Hiroshi Sano, 12 others “An Organic Light-Emitting Diode with    Highly Efficient Light Extraction Using Newly Developed Diffraction    Layer,” SID 08 DIGEST pp. 515 to 517

SUMMARY OF INVENTION

An object of the present invention is to provide a light-emitting devicewhich is improved in light-extraction efficiency; and a productionmethod for the light-emitting device; and a display containing thelight-emitting device. These can solve the above existing problems.

Means for solving the above problems are as follows.

<1> A light-emitting device including, in the order mentioned:

a light-emitting layer containing a light-emitting portion,

an intermediate layer, and

a fine concavo-convex pattern,

wherein the intermediate layer is disposed over a second surface of thelight-emitting layer which surface is opposite to a first surface of thelight-emitting layer,

wherein the fine concavo-convex pattern has a cross-sectional shapewhich has portions projected and recessed with respect to thelight-emitting layer, and reflects light emitted from the light-emittinglayer, and

wherein at least part of the intermediate layer has a refractive indexof 0.9n to 1.1n, where n denotes a refractive index of thelight-emitting portion with respect to light which has a mainlight-emitting wavelength.

<2> The light-emitting device according to <1> above, wherein the fineconcavo-convex pattern has a pitch interval of 0.01λ to 100λ where λdenotes a main light-emitting wavelength of light emitted from thelight-emitting layer.

<3> The light-emitting device according to any one of <1> and <2> above,wherein the light-emitting layer contains two or more of thelight-emitting portion.

<4> The light-emitting device according to any one of <1> to <3> above,wherein the fine concavo-convex pattern is made of heat-mode resist.

<5> The light-emitting device according to any one of <1> to <4> above,wherein the fine concavo-convex pattern includes a reflective layer.

<6> The light-emitting device according to <5> above, wherein thereflective layer has a thickness of 10 nm to 10,000 nm.

<7> The light-emitting device according to any one of <1> to <6> above,wherein the intermediate layer has a refractive index of 1.55 to 3.0.

<8> The light-emitting device according to any one of <1> to <7> above,wherein the fine concavo-convex pattern has a pitch interval of 50 nm to10 μm.

<9> The light-emitting device according to any one of <1> to <8> above,wherein the light-emitting layer further includes a seal layer forsealing the light-emitting portion, and wherein a material of the seallayer is any of an acrylic resin, an epoxy resin, a fluorine-containingresin, a silicone resin, a rubber resin and an ester resin.

<10> A production method for the light-emitting device according to anyone of <1> to <5> above, including:

forming a light-emitting layer containing a light-emitting portion,

forming an intermediate layer over a second surface of thelight-emitting layer which surface is opposite to a first surface of thelight-emitting layer, and

forming, over the intermediate layer, a fine concavo-convex patternhaving a cross-sectional shape which has portions projected and recessedwith respect to the light-emitting layer, the fine concavo-convexpattern reflecting light emitted from the light-emitting layer,

wherein the fine concavo-convex pattern is formed through heat-modelithography.

<11> A display including:

the light-emitting device according to <1> to <5> above.

The present invention can provide a light-emitting device which isimproved in light-extraction efficiency; and a production method for thelight-emitting device; and a display containing the light-emittingdevice, which can solve the above existing problems.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a cross-sectional view of an organic EL device as alight-emitting device of the present invention.

FIG. 2 is an explanatory cross-sectional view for a light-emittingdevice according to another embodiment of the present invention, and adisplay containing the light-emitting device.

FIG. 3 is an explanatory cross-sectional view of a conventionallight-emitting device.

FIG. 4 is a schematic view used for describing critical angle θ_(c) onthe interface between first and second layers.

FIG. 5 is a schematic view used for describing problems a conventionallight-emitting device has.

DESCRIPTION OF EMBODIMENTS

Next will be described in detail a light-emitting device of the presentinvention, a production method for the light-emitting device, and adisplay containing the light-emitting device.

(Light-Emitting Device)

A light-emitting device of the present invention includes alight-emitting layer containing a light-emitting portion; anintermediate layer; and a fine concavo-convex pattern in this order. Thefine concavo-convex pattern reflects light emitted from thelight-emitting layer and has a cross-sectional shape which has portionsprojected and recessed with respect to the light-emitting layer.

FIG. 1 is a schematic view of the structure of such a light-emittingdevice of the present invention. In this figure, an intermediate layer 5and a fine concavo-convex pattern 6 are disposed in this order over asecond surface 3B of a light-emitting layer 2 which surface is oppositeto a first surface 3A (light-emitting surface).

<Light-Emitting Layer>

The light-emitting layer 2 includes a light-emitting portion 4.

The device for the light-emitting portion 4 is not particularly limitedand may be appropriately selected depending on the purpose. Thelight-emitting portion may be, for example, an organic EL device, aninorganic EL device, an LED and a photodiode.

<<Seal Layer>>

In the light-emitting layer 2, the light-emitting portion 4 is sealedwith a seal layer 7.

The seal layer 7 prevents the light-emitting portion 4 from degrading inperformance due to oxygen and moisture as a result of exposure to air.

Also, the light-emitting layer 2 may contain a moisture absorbent or aninert liquid. The moisture absorbent is not particularly limited, andspecific examples thereof include barium oxide, sodium oxide, potassiumoxide, calcium oxide, sodium sulfate, calcium sulfate, magnesiumsulfate, phosphorus pentaoxide, calcium chloride, magnesium chloride,copper chloride, cesium fluoride, niobium fluoride, calcium bromide,vanadium bromide, molecular sieve, zeolite and magnesium oxide. Also,the inert liquid is not particularly limited, and specific examplesthereof include paraffins; liquid paraffins; fluorine-based solventssuch as perfluoroalkanes, perfluoroamines and perfluoroethers;chlorinated solvents; and silicone oils.

The material for the seal layer 7 is not particularly limited, andexamples thereof include acrylic resins, epoxy resins,fluorine-containing resins, silicone resins, rubber resins and esterresins. Among them, epoxy resins are preferred from the viewpoint ofpreventing water permeation. Among the epoxy resins, thermosetting epoxyresins and photo-curable epoxy resins are preferred.

The forming method for the seal layer 7 is not particularly limited, andexamples thereof includes a method by coating a resin solution, a methodby press-bonding or hot press-bonding a resin sheet, and a method bypolymerizing under dry conditions (e.g., vapor deposition andsputtering).

The thickness of the seal layer 7 is preferably 1 μm to 1 mm, morepreferably 5 μm to 100 μm, most preferably 10 μm to 50 μm. When thethickness is smaller than 1 μm, the inorganic film may be damaged uponmounting of the substrate. Whereas when the thickness is greater than 1mm, the light-emitting layer 2 becomes disadvantageously thick.

The light-emitting layer 2 may contain a sealing adhesive having thefunction of preventing permeation of moisture or oxygen from the edgesthereof.

The material for the sealing adhesive may be those used in the seallayer 7. Among them, epoxy resins are preferred from the viewpoint ofpreventing water permeation. Among the epoxy resins, photo-curable epoxyresins and thermosetting epoxy resins are preferred.

Also, a filler is preferably added to the above materials.

The filler to be incorporated into the seal layer 7 is preferablyinorganic materials such as SiO₂, SiO (silicon oxide), SiON (siliconoxynitride) and SiN (silicon nitride). The addition of the fillerincreases the viscosity of the sealant to improve production suitabilityand humidity resistance.

The sealing adhesive may also contain a desiccant. The desiccant ispreferably barium oxide, calcium oxide or strontium oxide.

The amount of the desiccant added to the sealing adhesive is preferably0.01% by mass to 20% by mass, more preferably 0.05% by mass to 15% bymass. When the amount is less than 0.01% by mass, the desiccant exhibitsreduced effects. Whereas when the amount is more than 20% by mass, it isdifficult to homogeneously disperse the desiccant in the sealingadhesive, which is not preferred.

In the present invention, the sealing adhesive containing the desiccantis applied in a predetermined amount using, for example, a dispenser.Thereafter, a second substrate is overlaid, followed by curing, tothereby obtain a functional device.

With respect to light having a main light-emitting wavelength λ (forexample, 550 nm, the same applies hereinafter), the refractive index n₁of the medium (seal layer 7) of the light-emitting layer 2 is about 1.5,the refractive index n₂ of air is about 1.0, and the refractive index n₃of the light-emitting portion 4 is about 1.8.

Here, in the present invention, total reflection occurring on the secondsurface 3B of the light-emitting layer 2 due to the difference betweenthe refractive index n₃ of the light-emitting portion 4 and therefractive index n₄ of the intermediate layer 5 is considered, and therefractive indices of them are not limited to the above values.

Notably, the main light-emitting wavelength refers to a peak wavelength.

The forming method for the light-emitting layer 2 is not particularlylimited and may be appropriately selected depending on the purpose. Forexample, the light-emitting layer can be formed by sequentially formingthe light-emitting portion 4 and the seal layer 7 with a vacuumfilm-forming method (e.g., vapor deposition).

<Intermediate Layer>

The refractive index n₄ of the intermediate layer 5 is 0.9n₃ (minimumvalue) to 1.1n₃ (maximum value), where n₃ denotes a refractive index ofthe light-emitting portion 4 with respect to light having a mainlight-emitting wavelength.

When the refractive index n₄ of the intermediate layer 5 is 0.9n₃ to1.1n₃, the light-emitting portion 4 has almost the same refractive indexas the intermediate layer 5. Thus, the light-emitting portion 4 and theintermediate layer 5 optically substantially function as one layer,avoiding total reflection on the second surface 3B of the light-emittinglayer; i.e., the interface between the light-emitting portion 4 and theintermediate layer 5. As a result, light traveling toward the secondsurface of the light-emitting layer 2 can enter the fine concavo-convexpattern 6.

Preferably, the refractive index n₄ of the intermediate layer 5 is0.95n₃ (minimum value) to 1.05n₃ (maximum value).

The material for the intermediate layer 5 is not particularly limitedand may be appropriately selected depending on the purpose. Examplesthereof include those having a light absorption peak wavelength (e.g.,dyes). When such materials are used, there can be employed light whosewavelength is longer than their light absorption peak wavelength. Also,the intermediate layer is formed by, for example, dispersinghigh-refractive-index microparticles (e.g., TiO₂ and ZrO₂) in a resin(e.g., an acrylic resin, a polycarbonate resin and a TAC resin).

The thickness of the intermediate layer 5 is not particularly limitedand may be appropriately selected depending on the purpose. It ispreferably 0.1 μm to 500 μm from the viewpoint of desired filmformation. Also, the minimum thickness is more preferably 0.5 μm ormore, particularly preferably 2 μm or more. The maximum thickness ismore preferably 100 μm or less, particularly preferably 50 μm or less.

With respect to light having a main light-emitting wavelength, theminimum value of the specific refractive index n₄ of the intermediatelayer 5 is preferably 1.55 or more, more preferably 1.65 or more,particularly preferably 1.7 or more; and the maximum value thereof ispreferably 3.0 or less, more preferably 2.6 or less, particularlypreferably 2 or less, from the viewpoint of stability of the material.

The forming method for the intermediate layer 5 is not particularlylimited and may be appropriately selected depending on the purpose.Examples thereof include spin coating, inkjet coating and slit coating.

Among them, spin coating is preferred from the viewpoint of attaininguniform coating.

<Fine Concavo-Convex Pattern>

The fine concavo-convex pattern 6 reflects light transmitted through theintermediate layer 5 toward the first layer 3A of the light-emittinglayer 2 for light extraction.

The shape of the fine concavo-convex pattern 6 is not particularlylimited, so long as the cross-sectional shape thereof has portionsprojected and recessed with respect to the light-emitting layer 2, andmay be, for example, a saw-like shape, a bellows-like shape and a squareshape.

The pitch interval of the fine concavo-convex pattern 6 is notparticularly limited and may be appropriately selected depending on thepurpose. From the viewpoint of increase in light quantity, the minimumpitch interval is preferably 0.01λ or more, more preferably 0.05λ ormore, still more preferably 0.1λ or more, particularly preferably 0.2λor more; and the maximum pitch interval is preferably 100λ or less, morepreferably 50λ or less, still more preferably 20λ or less, particularlypreferably 10λ or less. Here, λ denotes a main light-emitting wavelengthof light emitted from the light-emitting layer 2.

From the viewpoint of stable pattern formation, the minimum value of thespecific pitch interval of the fine concavo-convex pattern 6 ispreferably 50 nm or more, more preferably 100 nm or more, still morepreferably 200 nm or more, particularly preferably 300 nm or more; andthe maximum value thereof is preferably 10 μm or less, more preferably 6μm or less, still more preferably 3 μm or less, particularly preferably1 μm or less.

The forming method for the fine concavo-convex pattern 6 is notparticularly limited and may be appropriately selected depending on thepurpose.

For example, a light-absorbing resist (heat-mode resist) is applied, andthe thus-applied resist is treated through heat-mode lithography.

Alternatively, a light-absorbing resist is applied and treated throughheat-mode lithography to prepare a pattern (which is not necessarilymade of metal). And, the pattern is used for shape transfer throughimprinting or molding.

When formed in the above-described manner, the fine concavo-convexpattern can have a complicated shape containing a high-frequencycomponent, and thus is improved in light controllability.

<<Reflective Layer>>

A reflective layer (not shown) may be formed on at least one surface ofthe fine concavo-convex pattern 6. Notably, the fine concavo-convexpattern 6 itself may be made of light-reflective material.

The material for the reflective layer is not particularly limited andmay be appropriately selected depending on the purpose. Al, Ag, etc. arepreferred from the viewpoint of attaining high reflectivity.

The thickness of the reflective layer is not particularly limited andmay be appropriately selected depending on the purpose. It is preferably10 nm to 10,000 nm.

The reflective layer having a thickness of 10 nm or more is advantageousin terms of high reflectivity. The reflective layer having a thicknessof 10,000 nm or less is advantageous in terms of film formation.

The forming method for the reflective layer is not particularly limitedand may be appropriately selected depending on the purpose. Examplesthereof include various sputtering methods, vapor deposition methods andion plating methods.

Among them, DC sputtering is preferred from the viewpoint of attaininghigh reflectivity.

With reference to FIG. 1, next will be described the operation of thelight-emitting device 1 having the above-described structure (see FIG. 4in relation to critical angle θ_(c), etc.).

(1-1) Interface Between Light-Emitting Portion and Seal Layer

Light beam 10 a which is emitted from the light-emitting portion 4toward the first surface 3A of the light-emitting layer 2 and whoseincident angle is θ_(y1) smaller than critical angle θ_(c1) passesthrough the interface between the light-emitting portion 4 and the seallayer 7 to enter the seal layer 7.

Meanwhile, light beam 10 d whose incident angle is critical angle θ_(c)or angle θ_(x1) greater than critical angle θ_(c) is totally reflectedon the interface between the light-emitting portion 4 and the seal layer7 toward the second surface 3B of the light-emitting layer 2.

(1-2) Interface Between Light-Emitting Layer and Air (First Surface ofLight-Emitting Layer)

Light beam 10 a which is emitted from the light-emitting portion 4 toenter the seal layer 7 and whose incident angle is θ_(y2) smaller thancritical angle θ_(c2) at the first surface 3A of the light-emittinglayer 2 passes through the first surface 3A of the light-emitting layer2 to be emitted outside.

Meanwhile, light beam 10 d whose incident angle is critical angle θ_(c)or θ_(x2) greater than critical angle θ_(c) is totally reflected on thefirst surface of the light-emitting layer 2 toward the second surface 3Bof the light-emitting layer 2.

(2-1) Interface Between Light-Emitting Layer and Intermediate Layer(Second Surface of Light-Emitting Layer)

Light beams 10 b, 10 c and 10 d which travel toward the second surface3B of the light-emitting layer 2 are not totally reflected on the secondsurface 3B of the light-emitting layer (i.e., the interface between thelight-emitting portion 4 and the intermediate layer 5) and enter thefine concavo-convex pattern 6. This is because the refractive index n₃of the light-emitting portion 4 is almost the same as the refractiveindex n₄ of the intermediate layer 5 and thus, the light-emittingportion 4 and the intermediate layer 5 function optically substantiallyas one layer.

(2-2) Interface Between Intermediate Layer and Fine Concavo-ConvexPattern

Light beams 10 c, 10 d and 10 d, which travel toward the fineconcavo-convex pattern 6, are reflected on the fine concavo-convexpattern 6 toward the second surface 3B of the light-emitting layer 2,and pass through the intermediate layer 5, the light-emitting portion 4and the seal layer 7 to be emitted outside from the first surface 3A ofthe light-emitting layer 2 similar to the case of light beams 10 a.

As described above, since all the light beams 10 a to 10 d, which areemitted from the light-emitting layer 2, are emitted outside from thefirst surface 3A of the light-emitting layer 2, the light-emittingdevice 1 of the present invention is improved in light-extractionefficiency.

<Other Members>

Other members are not particularly limited and may be appropriatelyselected depending on the purpose. Examples thereof include a substrateand a protective layer.

<<Substrate>>

The substrate may be appropriately selected depending on the purposewithout particular limitation, and is preferably those which do notdiffuse or damp light emitted from an organic compound layer. Examplesof the materials for the substrate include inorganic materials such asyttria-stabilized zirconia (YSZ) and glass; and organic materials suchas polyesters (e.g., polyethylene terephthalate, polybutylene phthalateand polyethylene naphthalate), polystyrene, polycarbonate, polyethersulfone, polyarylate, polyimide, polycycloolefin, norbornene resins andpoly(chlorotrifluoroethylene).

For example, when the substrate is made of glass, the glass ispreferably alkali-free glass in order to reduce ions eluted from it.Also, when soda-lime glass is used for the material of the substrate, abarrier coat of silica, etc., is preferably provided on the substrate.The organic materials are preferably used since they are excellent inheat resistance, dimensional stability, solvent resistance, electricalinsulation and proccessability.

The shape, structure, size, etc. of the substrate are not particularlylimited and may be appropriately selected depending on, for example, theapplication/purpose of the formed light-emitting device. In general, theshape thereof is preferably a sheet shape. The substrate may have asingle- or multi-layered structure, and may be a single member or acombination of two or more members.

The substrate may be colorless or colored transparent. It is preferablycolorless transparent, since such colorless transparent substrate doesnot diffuse or damp light emitted from an organic light-emitting layer.

The substrate may be provided with a moisture permeation-preventinglayer (gas barrier layer) on the front or back surface thereof.

The moisture permeation-preventing layer (gas barrier layer) ispreferably made from an inorganic compound such as silicon nitride andsilicon oxide, and may be formed through, for example, high-frequencysputtering.

When a thermoplastic substrate is used, a hard coat layer, an under coatlayer and other layers may be additionally provided as necessary.

<<Protective Layer>>

The light-emitting device of the present invention may be entirelyprotected with a protective layer.

The material contained in the protective layer may be any materials, solong as they have the function of preventing permeation of water,oxygen, etc., which promote degradation of the device.

Specific examples thereof include metals such as In, Sn, Pb, Au, Cu, Ag,Al, Ti and Ni; metal oxides such as MgO, SiO, SiO₂, Al₂O₃, GeO, NiO,CaO, BaO, Fe₂O₃, Y₂O₃ and TiO₂; metal nitrides such as SiN_(x) andSiN_(x)O_(y); metal fluorides such as MgF₂, LiF, AlF₃ and CaF₂;polyethylenes, polypropylenes, polymethyl methacrylates, polyimides,polyureas, polytetrafluoroethylenes, polychlorotrifluoroethylens,polydichlorofluoroethylenes, copolymers of chlorotrifluoroethylens anddichlorofluoroethylenes, copolymers produced through compolymerizationof a monomer mixture containing tetrafluoroethylene and at least onecomonomer, fluorine-containing copolymers containing a ring structure inthe copolymerization main chain, water-absorbing materials each having awater absorption rate of 1% or more, and moisture permeation preventivesubstances each having a water absorption rate of 0.1% or less.

The method for forming the protective layer is not particularly limited.Examples thereof include a vacuum deposition method, a sputteringmethod, a reactive sputtering method, an MBE (molecular beam epitaxial)method, a cluster ion beam method, an ion plating method, a plasmapolymerization method (high-frequency excitation ion plating method), aplasma CVD method, a laser CVD method, a thermal CVD method, a gassource CVD method, a coating method, a printing method and a transfermethod.

(Display, Etc.)

A display of the present invention is not particularly limited, so longas it has a plurality of light-emitting portions, and may beappropriately selected depending on the purpose.

FIG. 2 exemplarily shows a light-emitting device 11 of the presentinvention which has a plurality of light-emitting portions 14, and adisplay 50 containing the light-emitting device. This display containsthe light-emitting device 11 which includes a light-emitting layer 12containing the light-emitting portions 14; an intermediate layer 15; anda fine concavo-convex pattern 16 in this order. The fine concavo-convexpattern 16 reflects light emitted from the light-emitting layer 12 andhas a cross-sectional shape which has portions projected and recessedwith respect to the light-emitting layer. The light-emitting device 11can be used as the display 50.

Notably, reference numerals 21 and 22 denote a protective layer and asubstrate, respectively.

As a method for forming a full color-type display, there are known, forexample, as described in “Monthly Display,” September 2000, pp. 33 to37, a tricolor light emission method by arranging, on a substrate,organic EL devices emitting lights corresponding to three primary colors(blue color (B), green color (G) and red color (R)); a white colormethod by separating white light emitted from an organic EL device forwhite color emission into three primary colors through a color filter;and a color conversion method by converting a blue light emitted from anorganic EL device for blue light emission into red color (R) and greencolor (G) through a fluorescent dye layer.

Further, by combining a plurality of organic EL devices emitting lightsof different colors which are obtained by the above-described methods,plane-type light sources emitting lights of desired colors can beobtained. For example, there are exemplified white light-emittingsources obtained by combining blue and yellow light emitting devices,and white light-emitting sources obtained by combining blue, green andred light light-emitting devices.

One exemplary light-emitting portion is an organic EL device, which willnext be described in detail. However, the light-emitting device is notlimited to the organic EL device and may be, for example, an inorganicEL device, an LED and a photodiode.

<Organic EL Layer>

The organic EL layer includes a substrate, a cathode, an anode and anorganic compound layer including an organic light-emitting layer,wherein the cathode and the anode are laid over the substrate, and theorganic light-emitting layer is sandwiched between the cathode and theanode. In terms of the function of a light-emitting device, at least oneof the anode and the cathode is preferably transparent.

As a lamination pattern of the organic compound layer, preferably, ahole-transport layer, an organic light-emitting layer and an electrontransport layer are laminated in this order from the anode side.Moreover, a hole-injection layer is provided between the hole-transportlayer and the cathode, and/or an electron-transportable intermediatelayer is provided between the organic light-emitting layer and theelectron transport layer. Also, a hole-transportable intermediate layermay be provided between the organic light-emitting layer and thehole-transport layer. Similarly, an electron-injection layer may beprovided between the cathode and the electron-transport layer.

Notably, each layer may be composed of a plurality of secondary layers.

The organic light-emitting layer corresponds to a light-emitting layer.Also, a transparent layer(s) of the anode, cathode, and organic compoundlayers (i.e., a layer(s) having optical transparency) correspond(s) to alight-transmitting layer.

Each of the constituent layers of the organic compound layer can besuitably formed in accordance with any of a dry film-forming method(e.g., a vapor deposition method and a sputtering method); a transfermethod; a printing method; an ink-jet method; and a spray method.

<<Anode>>

In general, the anode may be any material, so long as it has thefunction of serving as an electrode which supplies holes to the organiccompound layer. The shape, structure, size, etc. thereof are notparticularly limited and may be appropriately selected from knownelectrode materials depending on the application/purpose of thelight-emitting device. As described above, the anode is generallyprovided as a transparent anode.

Preferred examples of the materials for the anode include metals,alloys, metal oxides, conductive compounds and mixtures thereof.Specific examples include conductive metal oxides such as tin oxidesdoped with, for example, antimony and fluorine (ATO and FTO); tin oxide,zinc oxide, indium oxide, indium tin oxide (ITO) and indium zinc oxide(IZO); metals such as gold, silver, chromium and nickel; mixtures orlaminates of these metals and the conductive metal oxides; inorganicconductive materials such as copper iodide and copper sulfide; organicconductive materials such as polyaniline, polythiophene and polypyrrole;and laminates of these materials and ITO. Among them, conductive metaloxides are preferred. In particular, ITO is preferred from theviewpoints of productivity, high conductivity, transparency, etc.

The anode may be formed on the substrate by a method which isappropriately selected from wet methods such as printing methods andcoating methods; physical methods such as vacuum deposition methods,sputtering methods and ion plating method; and chemical methods such asCVD and plasma CVD methods, in consideration of suitability for thematerial for the anode. For example, when ITO is used as a material forthe anode, the anode may be formed in accordance with a DC orhigh-frequency sputtering method, a vacuum deposition method, or an ionplating method.

In the organic EL layer, a position at which the anode is to be formedis not particularly limited and may be appropriately determineddepending on the application/purpose of the light-emitting device.Preferably, the anode is formed on the substrate. In this case, theanode may be entirely or partially formed on one surface of thesubstrate.

Patterning for forming the anode may be performed by a chemical etchingmethod such as photolithography; a physical etching method such asetching by laser; a method of vacuum deposition or sputtering using amask; a lift-off method; or a printing method.

The thickness of the anode may be appropriately selected depending onthe material for the anode and is, therefore, not definitely determined.It is generally about 10 nm to about 50 μm, preferably 50 nm to 20 μm.

The resistance of the anode is preferably 10³ Ω/square or less, morepreferably 10² Ω/square or less. When the anode is transparent, it maybe colorless or colored. For extracting luminescence from thetransparent anode side, it is preferred that the anode has a lighttransmittance of 60% or higher, more preferably 70% or higher.

Concerning transparent anodes, there is a detail description in “TOUMEIDOUDEN-MAKU NO SHINTENKAI (Novel Developments in Transparent ElectrodeFilms)” edited by Yutaka Sawada, published by C.M.C. in 1999, thecontents of which can be applied to the present invention. When aplastic substrate having a low heat resistance is used, it is preferredthat ITO or IZO is used to form a transparent anode at a low temperatureof 150° C. or lower.

<<Cathode>>

In general, the cathode may be any material so long as it has thefunction of serving as an electrode which injects electrons into theorganic compound layer. The shape, structure, size, etc. thereof are notparticularly limited and may be appropriately selected from knownelectrode materials depending on the application/purpose of thelight-emitting device.

Examples of the materials for the cathode include metals, alloys, metaloxides, conductive compounds and mixtures thereof. Specific examplesthereof include alkali metals (e.g., Li, Na, K and Cs), alkaline earthmetals (e.g., Mg and Ca), gold, silver, lead, aluminum, sodium-potassiumalloys, lithium-aluminum alloys, magnesium-silver alloys and rare earthmetals (e.g., indium and ytterbium). These may be used individually, butit is preferred that two or more of them are used in combination fromthe viewpoint of satisfying both stability and electron-injectionproperty.

Among them, as the materials for forming the cathode, alkali metals oralkaline earth metals are preferred in terms of excellentelectron-injection property, and materials containing aluminum as amajor component are preferred in terms of excellent storage stability.

The term “material containing aluminum as a major component” refers to amaterial composed of aluminum alone; alloys containing aluminum and0.01% by mass to 10% by mass of an alkali or alkaline earth metal; orthe mixtures thereof (e.g., lithium-aluminum alloys andmagnesium-aluminum alloys).

The materials for the cathode are described in detail in JP-A Nos.02-15595 and 05-121172. The materials described in these literatures canbe used in the present invention.

The method for forming the cathode is not particularly limited, and thecathode may be formed by a known method. For example, the cathode may beformed by a method which is appropriately selected from wet methods suchas printing methods and coating methods; physical methods such as vacuumdeposition methods, sputtering methods and ion plating methods; andchemical methods such as CVD and plasma CVD methods, in consideration ofsuitability for the material for the cathode. For example, when a metal(or metals) is (are) selected as a material (or materials) for thecathode, one or more of them may be applied simultaneously orsequentially by a sputtering method.

Patterning for forming the cathode may be performed by a chemicaletching method such as photolithography; a physical etching method suchas etching by laser; a method of vacuum deposition or sputtering using amask; a lift-off method; or a printing method.

In the organic EL layer, a position at which the cathode is to be formedis not particularly limited, and the cathode may be entirely orpartially formed on the organic compound layer.

Furthermore, a dielectric layer having a thickness of 0.1 nm to 5 nm andbeing made, for example, of fluorides and oxides of an alkali oralkaline earth metal may be inserted between the cathode and the organiccompound layer. The dielectric layer may be considered to be a kind ofelectron-injection layer. The dielectric layer may be formed by, forexample, a vacuum deposition method, a sputtering method and an ionplating method.

The thickness of the cathode may be appropriately selected depending onthe material for the cathode and is, therefore, not definitelydetermined. It is generally about 10 nm to about 5 μm, and preferably 50nm to 1 μm.

Moreover, the cathode may be transparent or opaque. The transparentcathode may be formed as follows. Specifically, a 1 nm- to 10 nm-thickthin film is formed from a material for the cathode, and a transparentconductive material (e.g., ITO and IZO) is laminated on the thus-formedfilm.

<<Organic Compound Layer>>

The organic EL device of the present invention includes at least oneorganic compound layer including an organic light-emitting layer.Examples of the other organic compound layers than the organiclight-emitting layer include a hole-transport layer, an electrontransport layer, a hole blocking layer, an electron blocking layer, ahole-injection layer and an electron injection layer.

In the organic EL device, the respective layers constituting the organiccompound layer can be suitably formed by any of a dry film-formingmethod such as a vapor deposition method and a sputtering method; a wetfilm-forming method; a transfer method; a printing method; and anink-jet method.

<<<Organic Light-Emitting Layer>>>

The organic light-emitting layer is a layer having the functions ofreceiving holes from the anode, the hole-injection layer, or thehole-transport layer, and receiving electrons from the cathode, theelectron-injection layer, or the electron transport layer, and providinga field for recombination of the holes with the electrons for lightemission, when an electric field is applied.

The light-emitting layer in the present invention may be composed onlyof a light-emitting material, or may be a layer formed form a mixture ofa light-emitting dopant and a host material. The light-emitting dopantmay be a fluorescent or phosphorescent light-emitting material, and maycontain two or more species. The host material is preferably acharge-transporting material. The host material may contain one or morespecies, and, for example, is a mixture of a hole-transporting hostmaterial and an electron-transporting host material. Further, a materialwhich does not emit light nor transport any charge may be contained inthe organic light-emitting layer.

The organic light-emitting layer may be a single layer or two or morelayers. When it is two or more layers, the layers may emit lights ofdifferent colors.

The above light-emitting dopant may be, for example, a phosphorescentlight-emitting material (phosphorescent light-emitting dopant) and afluorescent light-emitting material (fluorescent light-emitting dopant).

The organic light-emitting layer may contain two or more differentlight-emitting dopants for improving color purity and/or expanding thewavelength region of light emitted therefrom. From the viewpoint ofdrive durability, it is preferred that the light-emitting dopant isthose satisfying the following relation(s) with respect to theabove-described host compound: i.e., 1.2 eV>difference in ionizationpotential (ΔIp)>0.2 eV and/or 1.2 eV>difference in electron affinity(ΔEa)>0.2 eV.

The fluorescent light-emitting material is not particularly limited andmay be appropriately selected depending on the purpose. Examples thereofinclude complexes containing a transition metal atom or a lanthanoidatom.

The transition metal atom is not particularly limited and may beselected depending on the purpose. Preferred are ruthenium, rhodium,palladium, tungsten, rhenium, osmium, iridium gold, silver, copper andplatinum. More preferred are rhenium, iridium and platinum. Particularlypreferred are iridium and platinum.

The lanthanoid atom is not particularly limited and may be appropriatelyselected depending on the purpose. Examples thereof include lanthanum,cerium, praseodymium, neodymium, samarium, europium, gadolinium,terbium, dysprosium, holmium, erbium, thulium, ytterbium and lutetium,with neodymium, europium and gadolinium being preferred.

Examples of ligands in the complex include those described in, forexample, “Comprehensive Coordination Chemistry” authored by G. Wilkinsonet al., published by Pergamon Press Company in 1987; “Photochemistry andPhotophysics of Coordination Compounds” authored by H. Yersin, publishedby Springer-Verlag Company in 1987; and “YUHKI KINZOKU KAGAKU—KISO TOOUYOU—(Metalorganic Chemistry—Fundamental and Application—)” authored byAkio Yamamoto, published by Shokabo Publishing Co., Ltd. in 1982.

Preferred examples of the ligands include halogen ligands (preferably,chlorine ligand), aromatic carbon ring ligands (preferably 5 to 30carbon atoms, more preferably 6 to 30 carbon atoms, still morepreferably 6 to 20 carbon atoms, particularly preferably 6 to 12 carbonatoms, such as cyclopentadienyl anion, benzene anion and naphthylanion); nitrogen-containing hetero cyclic ligands (preferably 5 to 30atoms, more preferably 6 to 30 carbon atoms, still more preferably 6 to20 carbon atoms, particularly preferably 6 to 12 carbon atoms, such asphenyl pyridine, benzoquinoline, quinolinol, bipyridyl andphenanthrorine), diketone ligands (e.g., acetyl acetone), carboxylicacid ligands (preferably 2 to 30 carbon atoms, more preferably 2 to 20carbon atoms, still more preferably 2 to 16 carbon atoms, such as aceticacid ligand), alcoholate ligands (preferably 1 to 30 carbon atoms, morepreferably 1 to 20 carbon atoms, still more preferably 6 to 20 carbonatoms, such as phenolate ligand), silyloxy ligands (preferably 3 to 40carbon atoms, more preferably 3 to 30 carbon atoms, still morepreferably 3 to 20 carbon atoms, such as trimethyl silyloxy ligand,dimethyl tert-butyl silyloxy ligand and triphenyl silyloxy ligand),carbon monoxide ligand, isonitrile ligand, cyano ligand, phosphorusligand (preferably 3 to 40 carbon atoms, more preferably 3 to 30 carbonatoms, still more preferably 3 to 20 carbon atoms, particularlypreferably, 6 to 20 carbon atoms, such as triphenyl phosphine ligand),thiolate ligands (preferably 1 to 30 carbon atoms, more preferably 1 to20 carbon atoms, still more preferably 6 to 20 carbon atoms, such asphenyl thiolate ligand) and phosphine oxide ligands (preferably 3 to 30carbon atoms, more preferably 8 to 30 carbon atoms, particularlypreferably 18 to 30 carbon atoms, such as triphenyl phosphine oxideligand), with nitrogen-containing hetero cyclic ligand being morepreferred.

The above-described complexes may be a complex containing one transitionmetal atom in the compound, or a so-called polynuclear complexcontaining two or more transition metal atoms. In the latter case, thecomplexes may contain different metal atoms at the same time.

Among them, specific examples of the light-emitting dopants includephosphorescence luminescent compounds described in Patent Literaturessuch as U.S. Pat. No. 6,303,238B1, U.S. Pat. No. 6,097,147, WO00/57676,WO00/70655, WO01/08230, WO01/39234A2, WO01/41512A1, WO02/02714A2,WO02/15645A1, WO02/44189A1, WO05/19373A2, JP-A Nos. 2001-247859,2002-302671, 2002-117978, 2003-133074, 2002-235076, 2003-123982 and2002-170684, EP1211257, JP-A Nos. 2002-226495, 2002-234894, 2001-247859,2001-298470, 2002-173674, 2002-203678, 2002-203679, 2004-357791,2006-256999, 2007-19462, 2007-84635 and 2007-96259. Among them, Ircomplexes, Pt complexes, Cu complexes, Re complexes, W complexes, Rhcomplexes, Ru complexes, Pd complexes, Os complexes, Eu complexes, Tbcomplexes, Gd complexes, Dy complexes and Ce complexes are preferred,with Ir complexes, Pt complexes and Re complexes being more preferred.Among them, Ir complexes, Pt complexes, and Re complexes each containingat least one coordination mode of metal-carbon bonds, metal-nitrogenbonds, metal-oxygen bonds and metal-sulfur bonds are still morepreferred. Furthermore, Ir complexes, Pt complexes, and Re complexeseach containing a tri-dentate or higher poly-dentate ligand areparticularly preferred from the viewpoints of, for example,light-emission efficiency, drive durability and color purity. Forexample, tris(2-phenylpyridine)iridium (Ir(ppy)₃) can be used.

The fluorescence luminescent dopant is not particularly limited and maybe appropriately selected depending on the purpose. Examples thereofinclude benzoxazole, benzoimidazole, benzothiazole, styrylbenzene,polyphenyl, diphenylbutadiene, tetraphenylbutadiene, naphthalimide,coumarin, pyran, perinone, oxadiazole, aldazine, pyralidine,cyclopentadiene, bis-styrylanthracene, quinacridone, pyrrolopyridine,thiadiazolopyridine, cyclopentadiene, styrylamine, aromaticdimethylidene compounds, condensed polyaromatic compounds (e.g.,anthracene, phenanthroline, pyrene, perylene, rubrene and pentacene),various metal complexes (e.g., metal complexes of 8-quinolynol,pyromethene complexes and rare-earth complexes), polymer compounds(e.g., polythiophene, polyphenylene and polyphenylenevinylene), organicsilanes and derivatives thereof.

Specific examples of the luminescent dopants include the followingcompounds, which should be construed as limiting the present inventionthereto.

The light-emitting dopant is contained in the light-emitting layer in anamount of 0.1% by mass to 50% by mass with respect to the total amountof the compounds generally forming the light-emitting layer. From theviewpoints of drive durability and external light-emitting efficiency,it is preferably contained in an amount of 1% by mass to 50% by mass,more preferably 2% by mass to 40% by mass.

Although the thickness of the light-emitting layer is not particularlylimited, in general, it is preferably 2 nm to 500 nm preferred. From theviewpoint of external light-emitting efficiency, it is more preferably 3nm to 200 nm, particularly preferably 5 nm to 100 nm.

The host material may be hole transporting host materials excellent inhole transporting property (which may be referred to as a “holetransporting host”) or electron transporting host compounds excellent inelectron transporting property (which may be referred to as an “electrontransporting host”).

Examples of the hole transporting host materials contained in theorganic light-emitting layer include pyrrole, indole, carbazole,azaindole, azacarbazole, triazole, oxazole, oxadiazole, pyrazole,imidazole, thiophene, polyarylalkane, pyrazoline, pyrazolone,phenylenediamine, arylamine, amino-substituted chalcone,styrylanthracene, fluorenone, hydrazone, stilbene, silazane, aromatictertiary amine compounds, styrylamine compounds, aromatic dimethylidinecompounds, porphyrin compounds, polysilane compounds,poly(N-vinylcarbazole), aniline copolymers, conductivehigh-molecular-weight oligomers (e.g., thiophene oligomers andpolythiophenes), organic silanes, carbon films and derivatives thereof.For example, 1,3-bis(carbazol-9-yl)benzene (mCP) can be used.

Among them, indole derivatives, carbazole derivatives, aromatic tertiaryamine compounds and thiophene derivatives are preferred. Also, compoundseach containing a carbazole group in the molecule are more preferred.Further, compounds each containing a t-butyl-substituted carbazole groupare particularly preferred.

The electron transporting host to be used in the organic light-emittinglayer preferably has an electron affinity Ea of 2.5 eV to 3.5 eV, morepreferably 2.6 eV to 3.4 eV, particularly preferably 2.8 eV to 3.3 eV,from the viewpoints of improvement in durability and decrease in drivevoltage. Also, it preferably has an ionization potential Ip of 5.7 eV to7.5 eV, more preferably 5.8 eV to 7.0 eV, particularly preferably 5.9 eVto 6.5 eV, from the viewpoints of improvement in durability and decreasein drive voltage.

Examples of the electron transporting host include pyridine, pyrimidine,triazine, imidazole, pyrazole, triazole, oxazole, oxadiazole,fluorenone, anthraquinonedimethane, anthrone, diphenylquinone,thiopyrandioxide, carbodiimide, fluorenylidenemethane, distyrylpyradine,fluorine-substituted aromatic compounds, heterocyclic tetracarboxylicanhydrides (e.g., naphthalene and perylene), phthalocyanine, derivativesthereof (which may form a condensed ring with another ring) and variousmetal complexes such as metal complexes of 8-quinolynol derivatives,metal phthalocyanine, and metal complexes having benzoxazole orbenzothiazole as a ligand.

Preferred electron transporting hosts are metal complexes, azolederivatives (e.g., benzimidazole derivatives and imidazopyridinederivatives) and azine derivatives (e.g., pyridine derivatives,pyrimidine derivatives and triazine derivatives). Among them, metalcomplexes are preferred in terms of durability. As the metal complexes(A), preferred are those containing a ligand which has at least onenitrogen atom, oxygen atom, or sulfur atom and which is coordinated withthe metal.

The metal ion contained in the metal complex is not particularly limitedand may be appropriately selected depending on the purpose. It ispreferably a beryllium ion, a magnesium ion, an aluminum ion, a galliumion, a zinc ion, an indium ion, a tin ion, a platinum ion or a palladiumion; more preferably is a beryllium ion, an aluminum ion, a gallium ion,a zinc ion, a platinum ion or a palladium ion; particularly preferablyis an aluminum ion, a zinc ion or a palladium ion.

Although there are a variety of known ligands to be contained in themetal complexes, examples thereof include those described in, forexample, “Photochemistry and Photophysics of Coordination Compounds”authored by H. Yersin, published by Springer-Verlag Company in 1987; and“YUHKI KINZOKU KAGAKU—KISO TO OUYOU—(Metalorganic Chemistry—Fundamentaland Application—)” authored by Akio Yamamoto, published by ShokaboPublishing Co., Ltd. in 1982.

The ligand is preferably nitrogen-containing heterocyclic ligands(preferably having 1 to 30 carbon atoms, more preferably 2 to 20 carbonatoms, particularly preferably 3 to 15 carbon atoms). It may be aunidentate ligand or a bi- or higher-dentate ligand. Preferred are bi-to hexa-dentate ligands, and mixed ligands of bi- to hexa-dentateligands with a unidentate ligand.

Examples of the ligand include azine ligands (e.g., pyridine ligands,bipyridyl ligands and terpyridine ligands); hydroxyphenylazole ligands(e.g., hydroxyphenylbenzoimidazole ligands, hydroxyphenylbenzoxazoleligands, hydroxyphenylimidazole ligands and hydroxyphenylimidazopyridineligands); alkoxy ligands (those having preferably 1 to 30 carbon atoms,more preferably 1 to 20 carbon atoms, particularly preferably 1 to 10carbon atoms, such as methoxy, ethoxy, butoxy and 2-ethylhexyloxy); andaryloxy ligands (those having preferably 6 to 30 carbon atoms, morepreferably 6 to 20 carbon atoms, particularly preferably 6 to 12 carbonatoms, such as phenyloxy, 1-naphthyloxy, 2-naphthyloxy,2,4,6-trimethylphenyloxy and 4-biphenyloxy).

Further examples include heteroaryloxy ligands (those having preferably1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularlypreferably 1 to 12 carbon atoms, examples of which include pyridyloxy,pyrazyloxy, pyrimidyloxy and quinolyloxy); alkylthio ligands (thosehaving preferably 1 to 30 carbon atoms, more preferably 1 to 20 carbonatoms, particularly preferably 1 to 12 carbon atoms, examples of whichinclude methylthio and ethylthio); arylthio ligands (those havingpreferably 6 to 30 carbon atoms, more preferably 6 to 20 carbon atoms,particularly preferably 6 to 12 carbon atoms, examples of which includephenylthio); heteroarylthio ligands (those having preferably 1 to 30carbon atoms, more preferably 1 to 20 carbon atoms, particularlypreferably 1 to 12 carbon atoms, examples of which include pyridylthio,2-benzimidazolylthio, 2-benzoxazolylthio and 2-benzothiazolylthio);siloxy ligands (those having preferably 1 to 30 carbon atoms, morepreferably 3 to 25 carbon atoms, particularly preferably 6 to 20 carbonatoms, examples of which include a triphenylsiloxy group, atriethoxysiloxy group and a triisopropylsiloxy group); aromatichydrocarbon anion ligands (those having preferably 6 to 30 carbon atoms,more preferably 6 to 25 carbon atoms, particularly preferably 6 to 20carbon atoms, examples of which include a phenyl anion, a naphthyl anionand an anthranyl anion); aromatic heterocyclic anion ligands (thosehaving preferably 1 to 30 carbon atoms, more preferably 2 to 25 carbonatoms, and particularly preferably 2 to 20 carbon atoms, examples ofwhich include a pyrrole anion, a pyrazole anion, a triazole anion, anoxazole anion, a benzoxazole anion, a thiazole anion, a benzothiazoleanion, a thiophene anion and a benzothiophene anion); and indolenineanion ligands. Among them, nitrogen-containing heterocyclic ligands,aryloxy ligands, heteroaryloxy groups, siloxy ligands, etc. arepreferred, and nitrogen-containing heterocyclic ligands, aryloxyligands, siloxy ligands, aromatic hydrocarbon anion ligands, aromaticheterocyclic anion ligands, etc. are more preferred.

Examples of the metal complex electron transporting host includecompounds described in, for example, JP-A Nos. 2002-235076, 2004-214179,2004-221062, 2004-221065, 2004-221068 and 2004-327313.

In the light-emitting layer, it is preferred that the lowest tripletexcitation energy (T1) of the host material is higher than T1 of thephosphorescence light-emitting material, from the viewpoints of colorpurity, light-emitting efficiency and drive durability.

Although the amount of the host compound added is not particularlylimited, it is preferably 15% by mass to 95% by mass with respect to thetotal amount of the compounds forming the light-emitting layer, in termsof light emitting efficiency and drive voltage.

<<Hole-Injection Layer and Hole-Transport Layer>>

The hole-injection layer and hole-transport layer are layers having thefunction of receiving holes from the anode or from the anode side andtransporting the holes to the cathode side. Materials to be incorporatedinto the hole-injection layer or the hole-transport layer may be alow-molecular-weight compound or a high-molecular-weight compound.

Specifically, these layers preferably contain, for example, pyrrolederivatives, carbazole derivatives, triazole derivatives, oxazolederivatives, oxadiazole derivatives, imidazole derivatives,polyarylalkane derivatives, pyrazoline derivatives, pyrazolonederivatives, phenylenediamine derivatives, arylamine derivatives,amino-substituted chalcone derivatives, styrylanthracene derivatives,fluorenone derivatives, hydrazone derivatives, stilbene derivatives,silazane derivatives, aromatic tertiary amine compounds, styrylaminecompounds, aromatic dimethylidine compounds, phthalocyanine compounds,porphyrin compounds, thiophene derivatives, organosilane derivatives andcarbon.

Also, an electron-accepting dopant may be incorporated into thehole-injection layer or the hole-transport layer of the organic ELdevice. The electron-accepting dopant may be, for example, an inorganicor organic compound, so long as it has electron accepting property andthe function of oxidizing an organic compound.

Specific examples of the inorganic compound include metal halides (e.g.,ferric chloride, aluminum chloride, gallium chloride, indium chlorideand antimony pentachloride) and metal oxides (e.g., vanadium pentaoxideand molybdenum trioxide).

As the organic compounds, those having a substituent such as a nitrogroup, a halogen, a cyano group and a trifluoromethyl group; quinonecompounds; acid anhydride compounds; and fullerenes may be preferablyused.

In addition, there can be preferably used compounds described in, forexample, JP-A Nos. 06-212153, 11-111463, 11-251067, 2000-196140,2000-286054, 2000-315580, 2001-102175, 2001-160493, 2002-252085,2002-56985, 2003-157981, 2003-217862, 2003-229278, 2004-342614,2005-72012, 2005-166637 and 2005-209643.

Among them, preferred are hexacyanobutadiene, hexacyanobenzene,tetracyanoethylene, tetracyanoquinodimethane,tetrafluorotetracyanoquinodimethane (F4-TCNQ), p-fluoranil, p-chloranil,p-bromanil, p-benzoquinone, 2,6-dichlorobenzoquinone,2,5-dichlorobenzoquinone, 1,2,4,5-tetracyanobenzene,1,4-dicyanotetrafluorobenzene, 2,3-dichloro-5,6-dicyanobenzoquinone,p-dinitrobenzene, m-dinitrobenzene, o-dinitrobenzene,1,4-naphthoquinone, 2,3-dichloronaphthoquinone, 1,3-dinitronaphthalene,1,5-dinitronaphthalene, 9,10-anthraquinone, 1,3,6,8-tetranitrocarbazole,2,4,7-trinitro-9-fluorenone, 2,3,5,6-tetracyanopyridine and fullereneC₆₀. More preferred are hexacyanobutadiene, hexacyanobenzene,tetracyanoethylene, tetracyanoquinodimethane,tetrafluorotetracyanoquinodimethane, p-fluoranil, p-chloranil,p-bromanil, 2,6-dichlorobenzoquinone, 2,5-dichlorobenzoquinone,2,3-dichloronaphthoquinone, 1,2,4,5-tetracyanobenzene,2,3-dichloro-5,6-dicyanobenzoquinone,4,4′,4″-tris(2-naphthylphenylamino)triphenylamine (2-TNATA),N,N′-dinaphthyl-N,N′-diphenyl-[1,1′-biphenyl]-4,4′-diamine (α-NPD) and2,3,5,6-tetracyanopyridine. Particularly preferred istetrafluorotetracyanoquinodimethane.

These electron-accepting dopants may be used alone or in combination.Although the amount of the electron-accepting dopant used depends on thetype of material, the dopant is preferably used in an amount of 0.01% bymass to 50% by mass, more preferably 0.05% by mass to 20% by mass,particularly preferably 0.1% by mass to 10% by mass, with respect to thematerial of the hole-transport layer.

The thicknesses of the hole-injection layer and the hole-transport layerare each preferably 500 nm or less in terms of reducing drive voltage.

The thickness of the hole-transport layer is preferably 1 nm to 500 nm,more preferably 5 nm to 200 nm, still more preferably 10 nm to 100 nm.The thickness of the hole-injection layer is preferably 0.1 nm to 200nm, more preferably 0.5 nm to 100 nm, still more preferably 1 nm to 100nm.

Each of the hole-injection layer and the hole-transport layer may have asingle-layered structure made of one or more of the above-mentionedmaterials, or a multi-layered structure made of a plurality of layerswhich are identical or different in composition.

<<<Electron-Injection Layer and Electron-Transport Layer>>>

The electron-injection layer and the electron-transport layer are layershaving the functions of receiving electrons from the cathode or thecathode side and transporting the electrons to the anode side. Theelectron-injection materials or electron-transport materials for theselayers may be low-molecular-weight or high-molecular-weight compounds.

Specific examples thereof include pyridine derivatives, quinolinederivatives, pyrimidine derivatives, pyrazine derivatives, phthalazinederivatives, phenanthoroline derivatives, triazine derivatives, triazolederivatives, oxazole derivatives, oxadiazole derivatives, imidazolederivatives, fluorenone derivatives, anthraquinodimethane derivatives,anthrone derivatives, diphenylquinone derivatives, thiopyrandioxidederivatives, carbodiimide derivatives, fluorenylidenemethanederivatives, distyrylpyradine derivatives, aryl tetracarboxylicanhydrides such as perylene and naphthalene, phthalocyanine derivatives,metal complexes (e.g., metal complexes of 8-quinolinol derivatives,metal phthalocyanine, and metal complexes containing benzoxazole orbenzothiazole as the ligand) and organic silane derivatives (e.g.,silole).

The electron-injection layer or the electron-transport layer in theorganic EL device of the present invention may contain an electrondonating dopant. The electron donating dopant to be introduced in theelectron-injection layer or the electron-transport layer may be anymaterial, so long as it has an electron-donating property and a propertyfor reducing an organic compound. Preferred examples thereof includealkali metals (e.g., Li), alkaline earth metals (e.g., Mg), transitionmetals including rare-earth metals, and reducing organic compounds.Among the metals, those having a work function of 4.2 eV or less areparticularly preferably used. Examples thereof include Li, Na, K, Be,Mg, Ca, Sr, Ba, Y, Cs, La, Sm, Gd and Yb. Also, examples of the reducingorganic compounds include nitrogen-containing compounds,sulfur-containing compounds and phosphorus-containing compounds.

In addition, there may be used materials described in, for example, JP-ANos. 06-212153, 2000-196140, 2003-68468, 2003-229278 and 2004-342614.

These electron donating dopants may be used alone or in combination. Theamount of the electron donating dopant used depends on the type of thematerial, but it is preferably 0.1% by mass to 99% by mass, morepreferably 1.0% by mass to 80% by mass, particularly preferably 2.0% bymass to 70% by mass, with respect to the amount of the material of theelectron transport layer.

The thicknesses of the electron-injection layer and theelectron-transport layer are each preferably 500 nm or less in terms ofreducing drive voltage.

The thickness of the electron-transport layer is preferably 1 nm to 500nm, more preferably 5 nm to 200 nm, particularly preferably 10 nm to 100nm. The thickness of the electron-injection layer is preferably 0.1 nmto 200 nm, more preferably 0.2 nm to 100 nm, particularly preferably 0.5nm to 50 nm.

Each of the electron-injection layer and the electron-transport layermay have a single-layered structure made of one or more of theabove-mentioned materials, or a multi-layered structure made of aplurality of layers which are identical or different in composition.

<<<Hole Blocking Layer>>>

The hole blocking layer is a layer having the function of preventing theholes, which have been transported from the anode side to thelight-emitting layer, from passing toward the cathode side, and may beprovided as an organic compound layer adjacent to the light-emittinglayer on the cathode side.

Examples of the compound forming the hole blocking layer includealuminum complexes (e.g.,bis-(2-methyl-8-quinolinolate)-4-(phenylphenolate)aluminum (BAlq)),triazole derivatives and phenanthroline derivatives (e.g., BCP).

The thickness of the hole blocking layer is preferably 1 nm to 500 nm,more preferably 5 nm to 200 nm, particularly preferably 10 nm to 100 nm.

The hole blocking layer may have a single-layered structure made of oneor more of the above-mentioned materials, or a multi-layered structuremade of a plurality of layers which are identical or different incomposition.

<<<Electron Blocking Layer>>>

An electron blocking layer is a layer having the function of preventingthe electrons, which have been transported from the cathode side to thelight-emitting layer, from passing toward the anode side, and may beprovided as an organic compound layer adjacent to the light-emittinglayer on the anode side in the present invention.

Examples of the compound forming the electron blocking layer includethose listed as a hole-transport material.

The thickness of the electron blocking layer is preferably 1 nm to 500nm, more preferably 5 nm to 200 nm, particularly preferably 10 nm to 100nm.

The electron blocking layer may have a single-layered structure made ofone or more of the above-mentioned materials, or a multi-layeredstructure made of a plurality of layers which are identical or differentin composition.

<<Driving>>

The organic EL layer can emit light when a DC voltage (which, ifnecessary, contains AC components) (generally 2 volts to 15 volts) or aDC is applied to between the anode and the cathode.

For the driving method of the organic EL layer, applicable are thosedescribed in, for example, JP-A Nos. 02-148687, 06-301355, 05-29080,07-134558, 08-234685 and 08-241047, Japanese Patent No. 2784615, andU.S. Pat. Nos. 5,828,429 and 6,023,308.

In the organic EL device, the light-extraction efficiency can be furtherimproved by various known methods. It is possible to increase thelight-extraction efficiency to improve the external quantum efficiency,for example, by processing the surface shape of the substrate (forexample, by forming a fine concavo-convex pattern), by controlling therefractive index of the substrate, the ITO layer and/or the organiclayer, or by controlling the thickness of the substrate, the ITO layerand/or the organic layer.

The organic EL layer may be used in a so-called top-emissionconfiguration in which light is extracted from the anode side.

The organic EL layer may have the configuration in whichcharge-generation layers are provided between a plurality oflight-emitting layers for the purpose of further enhancing thelight-emission efficiency.

The charge-generation layer has the function of generating charges(holes and electrons) during application of an electric field as well asthe function of injecting the generated charges into the adjacent layerto the charge-generation layer.

The charge-generation layer is made of any material, so long as it hasthe above-described functions. Also, it may be made of a single compoundor a plurality of compounds.

Specifically, the material/compound may be conductive materials,semi-conductive materials (like doped organic layers) or insulatingmaterials. Specific examples thereof include those disclosed in, forexample, JP-A Nos. 11-329748, 2003-272860 and 2004-39617.

More specific examples thereof include transparent conductive materialssuch as ITO and indium zinc oxide (IZO); fullerenes such as C₆₀;conductive organic compounds such as thiophene oligomers; conductiveorganic compounds such as metal phthalocyanines, metal-freephthalocyanines, metal porphyrins and metal-free porphyrins; metalmaterials such as Ca, Ag, Al, Mg—Ag alloy, Al—Li alloy and Mg—Li alloy;hole conductive materials; conductive materials; and mixtures thereof.

Examples of the hole conductive material include hole transport organicmaterials (e.g., 2-TNATA and NPD) doped with oxidants having electronattracting properties (e.g., F4-TCNQ, TCNQ and FeCl₃), P-type conductivepolymers and P-type semiconductors. Examples of the conductive materialinclude the electron transport organic materials doped with metals ormetal compounds having a work function of less than 4.0 eV, N-typeconductive polymers and N-type semiconductors. Examples of the N-typesemiconductor include N-type Si, N-type CdS and N-type ZnS. Examples ofthe P-type semiconductor include P-type Si, P-type CdTe and P-type CuO.

Further, the charge-generation layer may use an insulating material suchas V₂O₅.

The electric charge-generation layer may have a single-layered structureor be a laminate of a plurality of layers. Examples of the laminateinclude laminates of hole or electron conductive material and conductivematerials (e.g., a transparent conductive material and a metalmaterial); and a laminate of the hole and electron conductive materials.

In general, preferably, the film thickness or the material of thecharge-generation layer can be selected so that the transmittance withrespect to a visible light is 50% or more. The film thickness is notparticularly limited and may be appropriately determined depending onthe purpose. It is preferably 0.5 nm to 200 nm, more preferably 1 nm to100 nm, still more preferably 3 nm to 50 nm, particularly preferably 5nm to 30 nm.

The method for forming the charge-generation layer is not particularlylimited, and the above-described method for forming the organic compoundlayer can also be employed.

The charge-generation layer is formed between two or more of thelight-emitting layer. Also, a material having the function of injectingcharges may be incorporated into the adjacent layers to thecharge-generation layer on the anode and cathode sides. In order toincrease injection properties of electrons into the adjacent layers onthe anode side, electron-injecting compounds such as BaO, SrO, Li₂O,LiCl, LiF, MgF₂, MgO and CaF₂ may be laminated on a surface of thecharge-generation layer which faces the anode.

Other than the materials described above, the material for thecharge-generation layer may be selected based on the description in, forexamples, JP-A No. 2003-45676 and U.S. Pat. Nos. 6,337,492, 6,107,734and 6,872,472.

The organic EL layer may have a resonator structure. For example, on atransparent substrate are stacked a multi-layered film mirror composedof a plurality of laminated films having different reflective indices, atransparent or semi-transparent electrode, a light-emitting layer and ametal electrode. The light generated in the light-emitting layer isrepeatedly reflected between the multi-layered film mirror and the metalelectrode (which serve as reflection plates); i.e., is resonated.

In another preferred embodiment, a transparent or semi-transparentelectrode and a metal electrode are stacked on a transparent substrate.In this structure, the light generated in the light-emitting layer isrepeatedly reflected between the transparent or semi-transparentelectrode and the metal electrode (which serve as reflection plates);i.e., is resonated.

For forming the resonance structure, an optical path length determinedbased on the effective refractive index of two reflection plates, and onthe refractive index and the thickness of each of the layers between thereflection plates is adjusted to be an optimal value for obtaining adesired resonance wavelength. The calculation formula applied in thecase of the first embodiment is described in JP-A No. 09-180883. Thecalculation formula in the case of the second embodiment is described inJP-A No. 2004-127795.

EXAMPLES

The present invention will next be described by way of examples, whichshould not be construed as limiting the present invention thereto.

Example 1

A light-emitting device of Example 1 was fabricated as follows.

<Formation of Fine Concavo-Convex Pattern>

Through the below procedure, a fine concavo-convex pattern was formedand then provided with a reflective layer over the front surfacethereof.

<<Fine Concavo-Convex Portions>>

A thin film was formed on a glass substrate using compound A givenbelow; i.e., an ionically-bonded compound of the upper and lowercompounds (compound A has a high refractive index: n₄=1.73 with respectto light having a wavelength of 550 nm (main light-emittingwavelength)).

A material made of compound A (35 mg) was dissolved intetrafluoropropanol (1 mL). The resultant solution was dropped on theglass substrate which was being rotated at 300 rpm. Then, the rotationspeed was increased to 1,000 rpm, whereby a 200 nm-thick thin film wasformed.

The thin film was treated using a fine processing device (NEO1000,product of Pulstec Industrial Co., Ltd.) to form a fine concavo-convexpattern having a pitch interval of 0.6λ.

<<Reflective Layer>>

Through DC sputtering, a 100 nm-thick Ag thin film was formed on thefine concavo-convex pattern as a reflective layer.

<Formation of Intermediate Layer>

A material made of compound A (70 mg) was dissolved intetrafluoropropanol (1 mL). The resultant solution was dropped on thefine concavo-convex pattern-formed glass substrate which was beingrotated at 300 rpm. Then, the rotation speed was increased to 1,000 rpm,whereby a 400 nm-thick thin film was formed.

Here, the intermediate layer was formed so that the intermediate layer'srefractive index n₄ was the same as the light-emitting portion'srefractive index n₃ with respect to light having a main light-emittingwavelength.

<Formation of Organic EL Layer (Light-Emitting Portion)>

An organic EL device was formed using a resistance heating vacuumdeposition apparatus.

A 70 nm-thick ITO (indium tin oxide) layer was formed on theintermediate layer as an anode.

A 160 nm-thick hole-injection layer was formed on the ITO layer byco-evaporating 4,4′,4″-tris(2-naphthylphenylamino)triphenylamine (whichis abbreviated as “2-TNATA,” refer to the following structural formula)and tetrafluorotetracyanoquinodimethane (which is abbreviated as“F4-TCNQ,” refer to the following structural formula) so that the amountof F4-TCNQ was 1.0% by mass with respect to 2-TNATA.

A 10 nm-thick hole-transport layer was formed on the hole injectionlayer using N,N′-dinaphthyl-N,N′-diphenyl-[1,1′-biphenyl]-4,4′-diamine(which is abbreviated as “α-NPD,” refer to the following structuralformula).

A 30 nm-thick organic light-emitting layer was formed on the holetransport layer by co-evaporating 1,3-bis(carbazol-9-yl)benzene (whichis abbreviated as “mCP,” refer to the following structural formula) andgreen light-emitting material tris(2-phenylpyridine)iridium (which isabbreviated as “Ir(ppy)₃,” refer to the following structural formula) sothat the amount of the green light-emitting material was 5% by mass withrespect to mCP.

Subsequently, a 40 nm-thick electron transport layer was formed on theorganic light-emitting layer usingbis-(2-methyl-8-quinolinolate)-4-(phenylphenolate)aluminum (which isabbreviated as “BAlq,” refer to the following structural formula).

Further, patterning was performed using a shadow mask to form a 1nm-thick LiF layer, a 2 nm-thick Al layer and a 100 nm-thick ITO layer.

<Seal Layer>

A seal layer was formed on the organic EL layer using a mixture ofSiN_(x) and SiO_(x). The seal layer was found to have a refractive indexof about 1.8.

Example 2

The procedure of Example 1 was repeated, except that the intermediatelayer was formed so that the refractive index n₄ was the same as 0.96n₃rather than n₃, to thereby fabricate a light-emitting device of Example2.

Example 3

The procedure of Example 1 was repeated, except that the intermediatelayer was formed so that the refractive index n₄ was the same as 0.92n₃rather than n₃, to thereby fabricate a light-emitting device of Example3.

Example 4

The procedure of Example 1 was repeated, except that the intermediatelayer was formed so that the refractive index n₄ was the same as 0.9n₃rather than n₃, to thereby fabricate a light-emitting device of Example4.

Example 5

The procedure of Example 1 was repeated, except that the intermediatelayer was formed so that the refractive index n₄ was the same as 1.1n₃rather than n₃, to thereby fabricate a light-emitting device of Example5.

Example 6

The procedure of Example 1 was repeated, except that a fineconcavo-convex pattern was formed so that the pitch interval was 0.15λrather than 0.6λ, to thereby fabricate a light-emitting device ofExample 6.

Example 7

The procedure of Example 1 was repeated, except that a fineconcavo-convex pattern was formed so that the pitch interval was 105λrather than 0.6λ, to thereby fabricate a light-emitting device ofExample 7.

Comparative Example 1

The procedure of Example 1 was repeated, except that the intermediatelayer was formed so that the refractive index n₄ was the same as 0.85n₃rather than n₃, to thereby fabricate a light-emitting device ofComparative Example 1.

Comparative Example 2

The procedure of Example 1 was repeated, except that the intermediatelayer was formed so that the refractive index n₄ was the same as 1.15n₃rather than n₃, to thereby fabricate a light-emitting device ofComparative Example 2.

<Measuring Method>

<<Refractive Index>>

The refractive index of the organic EL layer (light-emitting portion),the intermediate layer or the seal layer was measured with anellipsometry method.

<<Pitch Interval of Fine Concavo-Convex Pattern>>

The pitch interval of the fine concavo-convex pattern was measured withan AFM (product name: OLS3500, product of OLYMPUS CORPORATION).

<<Light Quantity>>

The light emitted from the fabricated light-emitting device was measuredwith a multichannel spectrometer (product of Ocean Photonics, Inc.).

Notably, the main light-emitting wavelength of the light emitted fromthe EL layer (light-emitting portion) was measured with a multichannelspectrometer (product of Ocean Photonics, Inc.).

<Evaluation of Light-Extraction Efficiency>

Each of the fabricated light-emitting devices was evaluated forlight-extraction efficiency as follows.

The light-extraction efficiency was evaluated based on the ratio Q₂/Q₁,where Q₁ denotes a light quantity of a light-emitting device having nofine concavo-convex pattern (i.e., this value being regarded as 1) andQ₂ denotes a light quantity of each of the fabricated light-emittingdevices of Examples 1 to 7 and Comparative Examples 1 and 2. The resultsare shown in Table 1.

TABLE 1 Refractive index of intermediate Pitch interval of fineLight-extraction layer (×n₃) pattern (×λ) efficiency Ex. 1 1.00 0.6 1.30Ex. 2 0.96 0.6 1.25 Ex. 3 0.92 0.6 1.20 Ex. 4 0.90 0.6 1.15 Ex. 5 1.100.6 1.15 Ex. 6 1.00 0.15 1.20 Ex. 7 1.00 105 1.05 Comp. Ex. 1 0.85 0.60.90 Comp. Ex. 2 1.15 0.6 1.00

INDUSTRIAL APPLICABILITY

The light-emitting device of the present invention can be suitably usedin, for example, display devices, displays (light-emitting-type flatpanel displays (organic EL, inorganic EL, plasma)), backlights,electrophotography, illuminating light sources, recording light sources,exposing light sources, reading light sources, markers, interioraccessories, optical communication, LEDs and fluorescent tubes.

The invention claimed is:
 1. A light-emitting device comprising, in theorder mentioned: a light-emitting layer containing a plurality oflight-emitting portions, an intermediate layer, a reflective layer, anda fine concavo-convex pattern, the fine concavo-convex pattern comprisesa reflective material, wherein the intermediate layer is disposed over aplanar second surface of the light-emitting layer which surface isopposite to a first surface of the light-emitting layer, wherein thefine concavo-convex pattern has a cross-sectional shape which hasportions projected and recessed with respect to the planar secondsurface of the light-emitting layer and the reflective layer is disposedbetween the intermediate layer and fine concavo-convex pattern andreflects light emitted from the light-emitting layer, and wherein atleast part of the intermediate layer has a refractive index of 0.9n to1.1n, where n denotes a refractive index of the light-emitting portionwith respect to light which has a main light-emitting wavelength.
 2. Thelight-emitting device according to claim 1, wherein the fineconcavo-convex pattern has a pitch interval of 0.01λ to 100λ, where λdenotes a main light-emitting wavelength of light emitted from thelight-emitting layer.
 3. The light-emitting device according to claim 1,wherein the light-emitting layer contains two or more light-emittingportions.
 4. The light-emitting device according to claim 1, wherein thefine concavo-convex pattern is made of heat-mode resist.
 5. Thelight-emitting device according to claim 1, wherein the reflective layerhas a thickness of 10 nm to 10,000 nm.
 6. The light-emitting deviceaccording to claim 1, wherein the intermediate layer has a refractiveindex of 1.55 to 3.0.
 7. The light-emitting device according to claim 1,wherein the fine concavo-convex pattern has a pitch interval of 50 nm to10 μm.
 8. The light-emitting device according to claim 1, wherein thelight-emitting layer further comprises a seal layer for sealing thelight-emitting portions, and wherein a material of the seal layer is anyof an acrylic resin, an epoxy resin, a fluorine-containing resin, asilicone resin, a rubber resin and an ester resin.
 9. A productionmethod for a light-emitting device, comprising: forming a light-emittinglayer containing a light-emitting portion, forming an intermediate layerover a planar second surface of the light-emitting layer which surfaceis opposite to a first surface of the light-emitting layer, and forming,over the intermediate layer, a fine concavo-convex pattern comprising areflective material and having a cross-sectional shape which hasportions projected and recessed with respect to the planar secondsurface of the light-emitting layer, and a reflective layer is disposedbetween the fine concavo-convex pattern and intermediate layer forreflecting light emitted from the light-emitting layer, wherein the fineconcavo-convex pattern is formed through heat-mode lithography, whereinthe light-emitting device comprises, in the order mentioned: thelight-emitting layer containing the light-emitting portion, theintermediate layer, and the fine concavo-convex pattern, wherein theintermediate layer is disposed over the second surface of thelight-emitting layer which surface is opposite to the first surface ofthe light-emitting layer, wherein the fine concavo-convex pattern hasthe cross-sectional shape which has the portions projected and recessedwith respect to the light-emitting layer and reflects the light emittedfrom the light-emitting layer, and wherein at least part of theintermediate layer has a refractive index of 0.9n to 1.1n, where ndenotes a refractive index of the light-emitting portion with respect tolight which has a main light-emitting wavelength.
 10. The productionmethod according to claim 9, wherein the fine concavo-convex pattern hasa pitch interval of 0.01λ to 100λ, where λ denotes a main light-emittingwavelength of light emitted from the light-emitting layer.
 11. Theproduction method according to claim 9, wherein the intermediate layerhas a refractive index of 1.55 to 3.0.
 12. The production methodaccording to claim 9, wherein the fine concavo-convex pattern has apitch interval of 50 nm to 10 μm.
 13. A display comprising: alight-emitting device which comprises, in the order mentioned: alight-emitting layer containing a light-emitting portion, anintermediate layer, a reflective layer, a fine concavo-convex patterncomprising a reflective material, and wherein the intermediate layer isdisposed over a planar second surface of the light-emitting layer whichsurface is opposite to a first surface of the light-emitting layer,wherein the fine concavo-convex pattern has a cross-sectional shapewhich has portions projected and recessed with respect to the planarsecond surface of the light-emitting layer and the reflective layer isdisposed between the intermediate layer and fine concavo-convex patternand reflects light emitted from the light-emitting layer, and wherein atleast part of the intermediate layer has a refractive index of 0.9n to1.1n, where n denotes a refractive index of the light-emitting portionwith respect to light which has a main light-emitting wavelength. 14.The display according to claim 13, wherein the fine concavo-convexpattern has a pitch interval of 0.01λ to 100λ, where λ denotes a mainlight-emitting wavelength of light emitted from the light-emittinglayer.
 15. The display according to claim 13, wherein the intermediatelayer has a refractive index of 1.55 to 3.0.
 16. The display accordingto claim 13, wherein the fine concavo-convex pattern has a pitchinterval of 50 nm to 10 μm.